I'm working with a Flash application and periodically the
progress bar that displays as it loads will hang, only progressing
when the mouse is in motion (but the application runs fine in these
cases, if one wiggles the mouse around enough to let the progress
bar complete). The issue is intermittent but definitely not rare,
and I am completely perplexed by it.

Some background info, the application was developed in Flash
8 (ActionScript 2) and is delivered on a website via calls to the
SWFObject JavaScript library. Any ideas what could be causing
this?